Supraventricular tachycardia is the most common significant arrhythmia in children. If prolonged, it may cause heart failure and progress to cardiogenic shock warranting prompt treatment. The recommended interventions following vagal manoeuvres are intravenous adenosine and in the unstable patient electrical cardioversion. We present an infant with an unstable supraventricular tachycardia that was resistant to electrical cardioversion and recommended doses of adenosine. He reverted to sinus rhythm with a higher dose of adenosine, suggesting that such doses may be required in refractory supraventricular tachycardia.

The objective of this prospective study was to determine the nocturnal/diurnal distribution of peri-operative cardiac dysrhythmias in patients with coronary artery disease undergoing major vascular surgery. Eight patients with significant coronary artery disease undergoing major vascular surgery were studied. Continuous Holter monitoring was performed on each patient from approximately 1 h pre-operatively until 2–5 days post-operatively. Frequencies of isolated supraventricular and ventricular premature beats, and runs of supraventricular and ventricular premature beats were calculated for 6-h periods (00.00–06.00; 06.00–12.00; 12.00–18.00; 18.00–24.00 hours). Supraventricular tachycardia occurred significantly more frequently between 00.00 and 06.00 hours than during the other 6-h periods studied in the post-operative period following major vascular surgery.